A techno-economic investigation into performance enhancement of flat-plate solar collectors using reflective mirrors under atmospheric conditions in Kirkuk City, Iraq

Abstract

Solar energy, a sustainable and environmentally benign resource, has increasingly captivated scientific and engineering communities due to its ability to deliver clean energy with negligible operational expenses, notwithstanding its relatively high initial installation costs. The present investigation was undertaken to augment the thermal efficiency of a flat-plate solar collector by employing a reflective mirror under the climatic conditions of Kirkuk, Iraq. Two identical collectors were fabricated: one representing a conventional configuration and the other integrated with a reflective mirror to amplify the incident solar radiation and consequently elevate heat absorption. Experimental analyses were carried out during four consecutive months: December 2024 and January, February, and March 2025 at 1:00 p.m. In December, the mirror-assisted collector attained a thermal efficiency of 31.66%, compared with 28.99% for the conventional unit, indicating a 9.21% enhancement. In January, efficiency increased from 28.67% to 37.86%, corresponding to a 32.05% improvement. February recorded values of 39.59% and 36.65%, showing an 8.02% gain. March demonstrated the most substantial enhancement, as the modified collector reached 59.40% compared with 35.64% for the conventional system, a 66.66% increase. The outcomes verify that reflective augmentation significantly enhances the collector’s thermal performance, with the maximum efficiency observed in March due to the highest solar radiation intensity during this period.